Kadlag Kiran P, Rao M Jagadeeswara, Nag Angshuman
Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, India 411008.
J Phys Chem Lett. 2013 May 16;4(10):1676-81. doi: 10.1021/jz4007096. Epub 2013 May 3.
We report here a different kind of binary and ternary colloidal inorganic nanocrystals, where no capping ligand is used. The surfaces of these ligand-free nanocrystals were designed to exhibit negative charges and, therefore, electrostatically repel each other, forming a colloidal dispersion in a polar solvent. Undoped and Mn-doped ZnxCd1-xS nanocrystals were studied both in solution and close-packed films. While undoped samples exhibit poor luminescence because of surface defects, Mn-doped nanocrystals show strong luminescence both in solution (20% quantum efficiency) and the film. Strong Mn emission arises from the inner-core d electrons, which are less sensitive to nonradiative decay channels on the nanocrystal surface. Ligand-free AgInS2 nanocrystals exhibit donor-acceptor type luminescence. Our preliminary results suggest the possibility of electronic coupling between ligand-free nanocrystals in their film, and therefore, they are expected to be more suitable for electronic and optoelectronic applications compared to organic-capped nanocrystals.
我们在此报道了一种不同类型的二元和三元胶体无机纳米晶体，其中未使用封端配体。这些无配体纳米晶体的表面被设计为带有负电荷，因此彼此之间产生静电排斥，从而在极性溶剂中形成胶体分散体。对未掺杂和锰掺杂的ZnxCd1-xS纳米晶体在溶液和紧密堆积薄膜中都进行了研究。由于表面缺陷，未掺杂的样品发光性能较差，而锰掺杂的纳米晶体在溶液（量子效率为20%）和薄膜中均表现出强发光。强烈的锰发射源于内核d电子，其对纳米晶体表面的非辐射衰减通道不太敏感。无配体的AgInS2纳米晶体表现出供体-受体型发光。我们的初步结果表明，在其薄膜中无配体纳米晶体之间存在电子耦合的可能性，因此，与有机封端的纳米晶体相比，它们预计更适合用于电子和光电子应用。
